Ignore http_proxy while connecting to test WSGI server

urllib2.urlopen uses $http_proxy/$HTTP_PROXY environment variables by
default.  If set (and pointing to a remote host), then the WSGI tests
that spin up a local server and connect to it using
http://127.0.0.1:$port/ instead connect to $port *on the proxy*,
and (hopefully) fail.

This change uses urllib2 in a way that ignores proxy settings.

Change-Id: I4d94fcc06925d0c947345a07ae20352e1898e46d
Closes-Bug: #1356665
Merge "Ignore http_proxy while connecting to test WSGI server"